Supercharging mechanism for diesel engines



B. LOEFFLER SUPERCHARGING MECHANISM FOR DIESEL ENGINES 2 Sheets-Sheet 1Filed June 4, 1935 INVENTOR. flruna laefilar,

ATTORNEYfl Dec. 28, 1937. B. LOEFFLER 2,103,974

SUPERCHARGING MECHANISM FOR DIESEL ENGINES Filed June 4, 1955 2Sheets-Sheet 2 INVENTOR. Brazw 1406111121;

Patented Dec. 2 '1937 PATENT OFFICE.

SUPERCl-IARGING MECHANISM FOR DIESEL ENGINES Bruno Loeflier, Plainfield,N. J assignor to Mack Manufacturing Corporation,

Delaware a corporation of Application une 4, 1935,- Serial No. 24,824-

3 Claims.

The present invention relates to Diesel engines and embodies, morespecifically, an improved supercharging mechanism by means of whichadditional air may be introduced into the engine during predeterminedperiods of operation thereof. It is well known that the power output of2.

Diesel engine varies directly as the amount of air introduced thereto,the amount of fuel which is burned being dependent upon the amount ofair supplied to support combustion. The power output of Diesel engineshas heretofore been increased by providing supercharging mechanisms tosupply the total air introduced into the ,engine at an increasedpressure. The objection to this form of supercharging lies primarily inthe relatively great cost thereof due to the power required tocompress'and direct the entire air supply into the engine;

It is known that, during the normal operation of a Diesel engine, andwhere supercharging mechanism is not provided, only about eightyfive percent. of the air which wouldnormally be directed into the engine isavailable by reason of the suction effect of the piston and other lossesdue to friction, etc. In order that this loss of substantially fifteenper cent. may be retrieved,

and substantially one hundred per cent. of the air normally available besupplied to support combustion, the present invention provides amechanism for introducing a volume of air corresponding to such loss atthe proper. time during the engine operation. This additional air-issupplied through a separate channel and introduced into the engine in aparticularly advantageous fashion, as will be apparent presently.

It is a further object of the invention to provide a superchargingmechanism wherein additional air may be supplied to the engine duringpredetermined periods of operation thereof, the means for supplying theair'being of such characteras to introduce as much air as possibleduring the time available for the introduction thereof during certainperiods of operation of the engine.

A further object of the invention is to provide a superchargingmechanism wherein additional. I.

air may be introduced and supplied into the cylinder in such fashion asto supply the loss of air due to wire drawing through the inlet portupon closing movement of the air inlet valve.

A further object of the invention is to provide additional, orsupercharged, air may be introduced into the cylinder.

In the construction shown in the accompanying drawings, the invention isattained by the provision of an engine having ahead in which combustionand air chambers are formed to communicate with the engine cylinder, theair chamber being formed to receive supercharged air from an externalsource, in addition to the fuel and air mixture which is directed intothe combustion chamber during the compression stroke of'the piston. y

Further objects, not specifically enumerated above; will be apparent asthe invention is described ingreater detail in connection with theaccompanying drawings, wherein Figure 1 is a schematic illustration of aportion of the head of a Diesel engine embodying features of the presentinvention;

Figure 2 is an enlarged view in sectiomtaken through the combustion andair chamber shown in Figure 1, and showing the elements of the presentinvention in greater detail; I

Figure 3 is a diagrammatic illustration of the manner in which air isintroduced into the air chamber, the illustration comprising a valvelifttime curve;

Figure 4 is a diagrammatic representation ofv the inlet and exhaustcycles of operation of an engine inwhich is incorporated the presentinvention;

Figure 5 is a plan view showing the cylinder head of the mechanism shownin Figure 1, illustrating. the relative location of the engine valves.

' 1 With reference to Figure 1, a Diesel engine is illustrated at Illand provided with a head ll. The engine is formed with a cylinder [2with which a combustion chamber l3 communicates,

the combustion chamber in turn communicating through a port It with anair chamber l5 which may be formed in a suitable housing l6 or which mayconstitute partof the engine head. The 1 which is adapted to align withport I4 to establish communication between the combustion chamber l3 andthe air chamber I5. At the top of the cylindrical'valve iii, a valveseat 2| is formed, the seat being masked by a cylindrical maskingsurface 22 in which a valve 23 is received. The valve is adapted'to seatupon the seat 2| and thus prevent the introduction of air into the airchamber. A lever I 9 may be provided to rock the valve member IS in aproper fashion during the operation of the engine, thus enabling the airchamber to be disconnected from the combustion chamber during thestarting operation.

Above the valve member I9 is a chambered head 24 within which thevalve'stem 25 of the valve 23 is slidably mounted. The head 24 isprovided with a passage 26.which communicates with any suitable sourceof air pressure as, for example, a pump or accumulator within which airis maintained under a predetermined pressure.

Inasmuch as air is introduced into the air chamber I5 when the valve 23leaves the masking surface22, a greater amount of air is introduced intothe air chamber during the limited time available than in a constructionwherein no masking of the valve is provided. By masking the valve, theordinate 28 (representing zero valve velocity) is advanced to theposition indicated at 29. In this fashion, the time indicated betweenthe points 30 and 3| on the curve (representing the time during whichthe valve 23 establishes communication between the passage 26 and airchamber I5) witnesses a greater average valve area than with an unmaskedvalve.

Figure 4 represents diagrammatically the cycle of operation of theengine, the inner annulus 32 representing the operation of the inletvalve i1 and the outer annulus 33 the operation of the exhaut valve l8.It will be observed that the inlet valve is closed at 20 degrees onreturn stroke. The shaded segment 34 represents the time during whichthe supercharging valve 23 is open 1 only serves as a means forimproving the normal operation of the engine; but additionally serves asa means for providing a supercharging action which is independent of themain air supply introduced through the inlet valve. While the inventionhas been described with specific reference to the accompanying drawings,it is not to be limited save as defined in the appended claim I claim:

1. In combination with '2, Diesel engine head having a combustionchamber formed therein and an air chamber communicating therewith, asource of air under pressure, a valve between the air chamber andcombustion chamber, means to adjust the last-named valve, and a maskedvalve between the air chamber and the source of air, said masked valvemoving away from the source of air during its opening movement and beingformed to prevent communication between the chamber and source of airduring initial motion of the valve toward an open position whereby theamount of air entering the chamber is increased upon initial flowthereof past the valve.

2. In combination with a Diesel engine head having a combustion chamberformed therein and an air chamber communicating therewith, a source ofair under pressure, a cylindrical valve in the air chamber, means torotate the cylindrical valve to control the flow of gases between 'theair and the combustion chambers, a valve port in the cylindrical valve'coaxlally thereof communicating with the source of air, a valvecooperating with the port, and a cylindrical wall adjacent the port onthe side thereof adjacent the air chamber and of substantially the samesize as the valve, whereby the last-named valve is masked to preventcommunication between the chamber and source of air during initialmotion of the valve toward an open position.

3. In combination with a Diesel engine having a cylinder and a headhaving a combustion chamber formed therein separate from, butcommunicating with, the cylinder, an air chamber, the head having a portbetween the air chamber and combustion chamber to afford communicationtherebetween, adjustable valve means to vary the communication betweenthe air chamber and the combustion chamber, and an air inlet valve andvalve seat, said last named valve seat being formed on the saidadjustable valve means.

BRUNO LOEFFIER.

